Willebrord van royen snell biography of william

Willebrord Snellius[1][2] (born Willebrord Snel van Royen[3]) (1580[4] – 30 October 1626, Leiden) was a Dutch astronomer and mathematician. In the west, especially the English speaking countries, his name has been attached to the law of refraction of light for several centuries, but it is now known that this law was first discovered by Ibn Sahl in 984.

The same law was also investigated by Ptolemy and in the Middle Ages by Witelo, but due to lack of adequate mathematical instruments (trigonometric functions) their results were saved as tables, not functions.

The lunar crater Snellius is named after Willebrord Snellius.

Biography

Willebrord Snellius was born in Leiden, Netherlands.

In 1613 he succeeded his father, Rudolph Snel van Royen (1546–1613) as professor of mathematics at the University of Leiden. In 1615 he planned and carried into practice a new method of finding the radius of the earth, by determining the distance of one point on its surface from the parallel of lat